Many industrial processes produce olefins that are mixtures of linear internal olefins and branched alpha olefins. Olefins are frequently used in the manufacture of polymers or as drilling mud additives, or as intermediates for the production of oil additives and detergents. Depending upon the particular application, it would be desirable to manufacture a linear internal olefin composition having the greatest purity possible. For example, detergents manufactured from linear internal olefins are more biodegradable than detergents derived from many industrially manufactured olefin streams containing branched internal olefins. While pure species of linear internal olefins with a narrow carbon number range can be manufactured or produced in small quantities at a great cost, we have found that it would be particularly desirable to economically provide large quantities of a purified linear internal olefins from raw feedstocks containing a mixture of linear internal olefins and branched internal olefins.
Separating and isolating linear internal olefins from branched internal olefins is no easy task, especially when these species have similar or identical molecular weights or carbon numbers. Conventional distillation methods are inadequate to separate species of this type which have such closely related boiling points. The separation problem is further aggravated in that the linear internal olefin species not only needs to be separated from branched internal olefins, but also from everything else present in the feedstock mixture, such as saturated hydrocarbons. U.S. Pat. No. 4,946,560 described a process for the separation of internal olefins from alpha olefins by contacting a feedstock with anthracene to form an olefin adduct, separating the adduct from the feedstock, dissociating the anthracene-linear alpha olefin adduct through heat to produce anthracene and an olefin composition enriched in alpha olefin, and separating out the anthracene from the alpha olefin. We have found it desirable, however, to produce an olefin stream which is rich in linear internal olefins.